MGB Register Forum

Hi. When i fitted electronic ignition (Powerspark with silicone leads)I thought that one of the advantages would be easier starting. This does not seem to be the case with my car. From cold, I have to try 2-3 times to get the engine to fire and when it does it is very hesitant requiring the assistance of the starter motor until it eventually runs smoothly. Once warmed up and running smoothly everything is fine, smooth tick over, responsive, no mis-firing in fact exactly as it should be. Once warmed up re-starting is instant as would be expected.
Having fitted the Powerspark I set the timing at 20 deg btdc @ 1000rpm with vac disconnected. Carbs were then set with shoulder of needles flush with underside of piston. Jets were turned down 12 flats and subsequently weakened by a couple of flats to get a nice rise and fall as piston lifted. Air flow balanced nicely and tick over set at 750rpm. Everything was running nicely. The starting problem occurs when the car has been left for a few days but I usually pull out the choke just before stopping the engine to leave a rich mixture in the cylinders to assist starting, but the problem still exists. Don’t know if I am doing anything wrong but has anyone any thoughts that could help? Best regards Geoff.

I don't think the problem has anything to do with the ignition equipment. It sounds to me that the cold engine is being over-choked and flooded with neat petrol. I have similar issues with my SU carb equipped Dolomite. Use it every day and its fine. Leave it 2 or 3 weeks and the risk of flooding and doing exactly what you describe is high. Next time it happens shove the choke right in and give it full throttle to get some air into the engine. Once started use the choke gently to keep it running.

I would definitely NOT pull out the choke before stopping the engine. It isn't going to help at all with the next start and may actually harm the engine.

Thanks Bumpa. The comments about flooding the cold engine seem quite valid. I thought that leaving a rich mixture in the cylinders would help but that combined with full choke is probably too much for the ignition system to cope with. Have had the engine running briefly today. Started fairly well but when I turned it off I didn’t pull out the choke. So I will try starting it tomorrow with choke only and see if there is any improvement. Thanks Geoff

Pulling out the choke just before switching the engine off is not recommended as the neat petrol tends to wash the oil off the cylinder walls.

With a bit of a struggle managed to start first time with half choke. Will take your advice about pulling out the choke just before stopping the engine. Thanks Geoff

When I added silicone leads to my electronic ignition, I couldn't start from cold with full-choke as I always had.

Somewhere around half-choke was about right, and no choke at all was possible much, much more quickly.

Good luck!